Environmental and Genetic Control of Reproduction in Danthonia caespitosa Populations

1978 ◽  
Vol 26 (3) ◽  
pp. 351 ◽  
Author(s):  
KC Hodgkinson ◽  
JA Quinn
Keyword(s):  
Floral Induction ◽  
Flag Leaf ◽  
Day Length ◽  
Herbarium Specimens ◽  
Floral Initiation ◽  
Inflorescence Development ◽  
Southern Limit ◽  
The North ◽  
Eastern Australia ◽  
Controlled Environments

Seedlings and older plants of five populations of Danthonia caespitosa from south-eastern Australia were grown in controlled environments and in a transplant garden to determine the effect of day length, temperature, and vernalization of floral initiation and inflorescence development. The populations were selected from widely separated sites which spanned the latitudinal range (31-42°S.) for the species and extended from a hot, semiarid environment in the north to a relatively cool and moist temperature environment in the south. Examination of herbarium specimens indicated that seed set could occur as early as mid September at the northern limit for the species and not before mid January at the southern limit (Tasmania). In a uniform transplant garden located at Deniliquin (latitude 35° 23′S.) plants from the northern site reached anthesis 4 weeks earlier than plants from southern sites. Controlled environment experiments revealed that D. caespitosa is a long-day plant. Northern populations required a 9 . 5 hr day length or longer for floral induction compared with 11 hr or longer for southern populations. The number of days in inductive conditions (outside, day length 13.5 hr) required for floral initiation was 5-7 for the three most northern populations and 21-25 days for the two southern populations. Inflorescence development (initiation to flag leaf stage) was considerably slower in southern populations. All but the most northern population responded to vernalization. Flowering was earlier in temperatures that were optimal for plant growth. At high temperatures (36/31°C day/night) flowering was not significantly delayed for the three most northern populations, but was for the two southern populations, and florets contained caryopses in only the three northern populations. These results suggest that in cool and moist temperate habitats reproduction of this species is programmed by day length and temperature effects on floral initiation and development to coincide with a predictable growing season, whereas in hot semiarid habitats this control is relaxed, which permits opportunistic reproduction whenever soil moisture and temperature permit growth.

Day-length influence on reproductive development and tillering in ‘Fergus’ barley

1975 ◽  
Vol 53 (23) ◽  
pp. 2770-2775 ◽  
Author(s):  
D. T. Fairey ◽  
L. A. Hunt ◽  
N. C. Stoskopf
Keyword(s):  
Hordeum Vulgare ◽  
Reproductive Development ◽  
Tiller Number ◽  
Day Length ◽  
Floral Initiation ◽  
Internode Elongation ◽  
Spikelet Number ◽  
Hordeum Vulgare L ◽  
Initial Formation ◽  
Double Ridge

Effects of variation in day length on spikelet and tiller development were studied in a two-rowed barley, Hordeum vulgare L. cultivar ‘Fergus.’ Spikelet number and the length of the spikelet-forming phase increased with progressive reductions in day length from 24 to 12 h. However, increases in spikelet number were offset by abortion of spikelet primordia during spikelet differentiation and elongation of the stem internodes. Floral initiation occurred at all day lengths, but intemode elongation and heading were markedly delayed at 12 h. The cessation of spikelet initial formation and the beginning of internode elongation did not occur simultaneously in any day length. The latter began just before or at double ridge formation.Tiller numbers were highest at 12 h and progressively decreased in longer day lengths. Each plant produced four primary tillers at all day lengths, and differences in tiller number were accounted for by secondary and tertiary tiller production.

scholarly journals Morphological variation in Leptorhynchos squamatus (Gnaphalieae: Asteraceae)

2002 ◽  
Vol 15 (2) ◽  
pp. 205 ◽  
Author(s):  
Christina Flann ◽  
Pauline Y. Ladiges ◽  
Neville G. Walsh
Keyword(s):  
High Altitude ◽  
Morphological Variation ◽  
Environmental Conditions ◽  
Leaf Size ◽  
Alpine Plants ◽  
The Other ◽  
Herbarium Specimens ◽  
South Eastern ◽  
Eastern Australia ◽  
Low Altitude

A study of morphological variation in Leptorhynchos squamatus (Labill.) Less. across its range in south-eastern Australia was undertaken to test the hypothesis that L. squamatus includes two taxa. Phenetic pattern analyses of both field-collected and herbarium specimens on the basis of morphology confirmed two major groups. Bract, cypsela, pappus bristle and leaf characters were particularly important in separating the two groups. The taxa are separated by altitude differences with one being a low-altitude plant found in many habitats and the other being a high-altitude taxon that is a major component of alpine meadows. Lowland plants have dark bract tips, fewer and wider pappus bristles than alpine plants, papillae on the cypselas and more linear leaves. A somewhat intermediate population from the Major Mitchell Plateau in the Grampians shows some alpine and some lowland characters but is included in the lowland taxon. Seeds from five populations (two alpine, two lowland and Major Mitchell) were germinated and plants grown for 18 weeks under four controlled sets of environmental conditions. The experiment showed that leaf size and some other characters are affected by environmental conditions, but that there are underlying genetic differences between the lowland and alpine forms. Leptorhynchos squamatus subsp. alpinus Flann is described here to accommodate the highland taxon.

scholarly journals A new species of Cochemiea (Cactaceae, Cacteae) from Sinaloa, Mexico

2020 ◽  
Author(s):  
Leccinum Jesús García Morales ◽  
Rodrigo Homero González González ◽  
Jesús García Jiménez ◽  
Duilio Iamonico
Keyword(s):  
New Species ◽  
Conservation Status ◽  
Relevant Literature ◽  
Small Population ◽  
Critically Endangered ◽  
Herbarium Specimens ◽  
The North ◽  
Hummingbird Pollination ◽  
Diagnostic Key ◽  
A New Species

Background and Aims: Cochemiea is a genus which currently comprises five species occurring in Mexico. It is morphologically characterized by cylindrical decumbent to prostrate stems and by a long red-scarlet zygomorphic perianth, presumably specialized for hummingbird pollination. As part ofthe ongoing taxonomic studies on the North Mexican flora, a population discovered by Thomas Linzen in 2012 in central Sinaloa (Mexico), previously identified as Mammillaria sp., actually refers to a Cochemiea species and cannot be ascribed to any of the known species of that genus. As a consequence,we here propose to describe this population as a a new species for science.Methods: The work is based on field surveys (autumn 2018 and spring 2019) in central Sinaloa, examination of herbarium specimens, and analysis of relevant literature. Its conservation status was assessed following the guidelines of the IUCN; AOO and EOO were calculated with the programGeoCAT.Key results: Cochemiea thomasii is described and illustrated from Sinaloa. The new species is morphologically similar to C. halei from which it differs by the hanging stems, the larger conical tubercles, less numerous and shorter central spines, and the ovoid fruits. A diagnostic key of the knownCochemiea species is included.Conclusions: Cochemiea thomasii is endemic to the state of Sinaloa where it occupies a small area. On the basis of the criteria B2a (geographic range) and C (small population) of IUCN, the new species can be assessed as Critically Endangered (CR) or Vulnerable (VU). Adopting the precautionary approach, Cochemiea thomasii is considered as Critically Endangered (CR).

scholarly journals Managing flowering time in Miscanthus and sugarcane to facilitate intra- and intergeneric crosses

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0240390
Author(s):  
Hongxu Dong ◽  
Lindsay V. Clark ◽  
Xiaoli Jin ◽  
Kossonou Anzoua ◽  
Larisa Bagmet ◽  
...  
Keyword(s):  
Flowering Time ◽  
High Latitude ◽  
Floral Induction ◽  
Day Treatment ◽  
Day Length ◽  
Close Relative ◽  
Short Day ◽  
Culm Length ◽  
Low Latitudes ◽  
Short Days

Miscanthus is a close relative of Saccharum and a potentially valuable genetic resource for improving sugarcane. Differences in flowering time within and between Miscanthus and Saccharum hinders intra- and interspecific hybridizations. A series of greenhouse experiments were conducted over three years to determine how to synchronize flowering time of Saccharum and Miscanthus genotypes. We found that day length was an important factor influencing when Miscanthus and Saccharum flowered. Sugarcane could be induced to flower in a central Illinois greenhouse using supplemental lighting to reduce the rate at which days shortened during the autumn and winter to 1 min d-1, which allowed us to synchronize the flowering of some sugarcane genotypes with Miscanthus genotypes primarily from low latitudes. In a complementary growth chamber experiment, we evaluated 33 Miscanthus genotypes, including 28 M. sinensis, 2 M. floridulus, and 3 M. ×giganteus collected from 20.9° S to 44.9° N for response to three day lengths (10 h, 12.5 h, and 15 h). High latitude-adapted M. sinensis flowered mainly under 15 h days, but unexpectedly, short days resulted in short, stocky plants that did not flower; in some cases, flag leaves developed under short days but heading did not occur. In contrast, for M. sinensis and M. floridulus from low latitudes, shorter day lengths typically resulted in earlier flowering, and for some low latitude genotypes, 15 h days resulted in no flowering. However, the highest ratio of reproductive shoots to total number of culms was typically observed for 12.5 h or 15 h days. Latitude of origin was significantly associated with culm length, and the shorter the days, the stronger the relationship. Nearly all entries achieved maximal culm length under the 15 h treatment, but the nearer to the equator an accession originated, the less of a difference in culm length between the short-day treatments and the 15 h day treatment. Under short days, short culms for high-latitude accessions was achieved by different physiological mechanisms for M. sinensis genetic groups from the mainland in comparison to those from Japan; for mainland accessions, the mechanism was reduced internode length, whereas for Japanese accessions the phyllochron under short days was greater than under long days. Thus, for M. sinensis, short days typically hastened floral induction, consistent with the expectations for a facultative short-day plant. However, for high latitude accessions of M. sinensis, days less than 12.5 h also signaled that plants should prepare for winter by producing many short culms with limited elongation and development; moreover, this response was also epistatic to flowering. Thus, to flower M. sinensis that originates from high latitudes synchronously with sugarcane, the former needs day lengths >12.5 h (perhaps as high as 15 h), whereas that the latter needs day lengths <12.5 h.

Accelerating growth of silver fir seedlings under controlled environments

1987 ◽  
Vol 17 (8) ◽  
pp. 835-839
Author(s):  
Sunil Puri ◽  
M. A. Tak
Keyword(s):  
Positive Response ◽  
Maximum Growth ◽  
Day Length ◽  
Silver Fir ◽  
N Application ◽  
Nitrogen Levels ◽  
Shoot Ratio ◽  
Percent Increase ◽  
Controlled Environments ◽  
Shoot Weight

Studies on Abiespindrow seedlings were conducted to accelerate and attain maximum growth under controlled environmental conditions. Seedlings of age 7, 19, and 31 months collected from Manali, Shilaru, and Kashmir provenances were treated for 90 days with four photoperiods (natural day length and 12, 18, and 24 h light) and two nitrogen levels (1.0 and 1.5 g/seedling). A positive response to light and N application was observed. Initially, light had no effect on roots (up to 45 days) but later on a significant increase in length and weight of roots was observed. Root to shoot ratio decreased with light but increased with N applied to seedlings. The interaction among photoperiod, N, provenance, and age, calculated from analysis of variance, was significant for root length and root and shoot weight at 45 and 90 days. The maximum percent increase in growth and biomass was observed in the 1-0 age from the Kashmir provenance.

The North American ginseng inflorescence: development, floret abscission zone, and the effect of ethylene

2001 ◽  
Vol 79 (9) ◽  
pp. 1048-1056 ◽  
Author(s):  
Andrea E Fiebig ◽  
John TA Proctor ◽  
Usher Posluszny ◽  
Dennis P Murr
Keyword(s):  
North American ◽  
American Ginseng ◽  
Abscission Zone ◽  
Panax Quinquefolius ◽  
Inflorescence Development ◽  
Zone Formation ◽  
Zone Length ◽  
The North ◽  
Seed Head ◽  
Industry Practice

Characterization of the North American ginseng (Panax quinquefolius L.) inflorescence, the floret abscission zone, and its stimulation by ethylene were undertaken to gain insights into the potential for floret abscission induction as a replacement for the industry practice of expensive manual removal of the inflorescence. In each of 3 years, peduncle length of 3-year-old cultivated ginseng inflorescences increased rapidly in June, reaching maximal values of 140–180 mm. During this period, seed head diameter also increased to about 35 mm, while seed head fresh mass increased in July and August to 6.5–8.0 g. Flowering in 1996 and 1997 began in the last 2 weeks of June and lasted through July, with open flowers never exceeding 35%. Anatomical studies and manual dissection of 1- and 3-year-old perennating buds revealed development of the floral primordia first at their periphery and progressing centripetally. Stamen initials were seen as a pentamerous whorl just under the petal primordia, and the characteristic inferior ovary initiated as a slight depression at the centre of the floral meristem. Sections through 3-year-old inflorescences harvested on May 23, 1996, showed that distal floral apices had already formed constriction zones between the flower and the pedicel, indicating the position of the abscission zone. Length of time to ethylene-induced abscission zone formation was less than 24 h in 3-year-old ginseng harvested on July 23, 1997. The abscission threshold for ginseng berry drop was in the range of 10-100 µL·L–1 ethylene.Key words: anatomy, flowering, Panax quinquefolius, perennating bud.

Le synclinal danien-eocene de La Mourotte (Var)

1962 ◽  
Vol S7-IV (1) ◽  
pp. 87-91 ◽  
Author(s):  
Fernand Touraine
Keyword(s):  
Upper Jurassic ◽  
The South ◽  
Northern Limit ◽  
Southern Limit ◽  
The North ◽  
Bird Eggs ◽  
Tectonic Study ◽  
Dinosaur Eggs

Abstract Results of a stratigraphic and tectonic study of the Mourotte syncline, Provence, France, divide the structure into three parts. The northern part is composed of Hauterivian littoral beds containing Danian dinosaur eggs. The Danian limestone-sandstone series disappears at La Neuve while the marly upper Danian beds continue to the extreme northern limit of the syncline. In the central part the Hauterivian wedges out, and toward its southern limit the substratum is entirely upper Jurassic. In the southern part, the Danian limestones are only visible on the northeast border. Bird eggs collected in the area assign the southern part of the syncline to the Thanetian. Overturning is less noticeable in the north, becoming acute toward the south where the syncline is tightly overturned.

Genetic variation in Trithuria inconspicua and T. filamentosa (Hydatellaceae): a new subspecies and a hypothesis of apomixis arising within a predominantly selfing lineage

2019 ◽  
Author(s):  
Rob D. Smissen ◽  
Kerry A. Ford ◽  
Paul D. Champion ◽  
Peter B. Heenan
Keyword(s):  
Genetic Variation ◽  
New Zealand ◽  
Morphological Variation ◽  
Genetic Distances ◽  
Herbarium Specimens ◽  
Minimum Evolution ◽  
The North ◽  
Genetic Groups ◽  
Morphological Differences ◽  
High Level

While examining herbarium specimens of Trithuria inconspicua Cheeseman, we observed differences in the stigmatic hairs among plants from New Zealand’s North and South Islands. This motivated us to assess genetic and morphological variation within this species and its sister T. filamentosa Rodway from Tasmania. Samples were collected from lakes in the three disjunct geographic areas where the two species occur. Genetic variation in both species was assessed with simple sequence-repeat (SSR, microsatellite) markers and analyses of genetic distances. We also compared the morphology of northern and southern New Zealand T. inconspicua using fresh material. Samples of each species clustered together in a minimum evolution tree built from genetic distances. Trithuria filamentosa had more genetic diversity than did T. inconspicua. Within T. inconspicua, plants from lakes in the North Island and the South Island formed discrete genetic groups diagnosable by subtle morphological differences. Low levels of heterozygosity in both species are consistent with a high level of selfing, as suggested for other co-sexual Trithuria species, but unusual for a putative apomict. On the basis of genetic and morphological variation, we propose recognition of the northern New Zealand and southern New Zealand lineages of T. inconspicua at subspecies rank.

Chondrilla juncea L. in Australia. I. Some factors affecting flowering

1966 ◽  
Vol 17 (4) ◽  
pp. 457 ◽  
Author(s):  
EG Cuthbertson
Keyword(s):  
Dark Period ◽  
Critical Factor ◽  
Photoperiodic Response ◽  
Day Length ◽  
Floral Initiation ◽  
Factors Affecting ◽  
Two Stages ◽  
Relationship Of ◽  
The Relationship ◽  
Chondrilla Juncea

The interaction between day length and vernalization, and the influence of growth temperature on flowering, in Chondrilla juncea L. (skeleton weed) have been studied. Bolting and floral initiation in unvernalized plants were suppressed in a 9-hr photoperiod. Increasing the photoperiod beyond 12 hr resulted in progressively earlier bolting and floral initiation, the critical day length being slightly less than 12 hr. Interrupting a 16-hr dark period by 1 hr of low-intensity light near its centre caused some plants to flower. Prior vernalization further accelerated bolting and flowering and reduced the dependence on day length. Vernalization, however, was not an obligate requirement. Post-bolting development was favoured by high temperatures. It was concluded that flowering in skeleton weed occurred in two stages. The first or photo-inductive phase was controlled by at least two partial processes. These were vernalization and a photoperiodic response in which the length of the dark period was the critical factor. The relationship of the flowering processes to the distribution of skeleton weed in Australia is discussed briefly.

The reproductive biology and ecology of Gammarus duebeni (Crustacea: Amphipoda) in southern England

1983 ◽  
Vol 63 (3) ◽  
pp. 517-540 ◽  
Author(s):  
Martin Sheader
Keyword(s):  
Life Cycle ◽  
Egg Production ◽  
Breeding Strategy ◽  
Female Size ◽  
Temperature Dependent ◽  
Southern Limit ◽  
Factors Affecting ◽  
North East ◽  
The North ◽  
Test Estuary

A study was made of the life cycle and reproductive ecology of Gammarus duebeni in the Test Estuary on the south coast of England. The species is towards the southern limit of its distributional range in the north-east Atlantic, which results in breeding continuing throughout much of the year. The breeding strategy employed was found to vary with season. The size of eggs produced and the rate of egg production were both temperature dependent, whereas the proportion of production expended on eggs and the number of eggs per brood, although probably influenced by temperature appeared to be controlled by food availability and female size. Factors affecting the mortality of eggs within the marsupium and breeding synchrony were considered in relation to season. The life cycle consisted of two major overlapping generations.

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